Micronutrients and susceptibility to infection

Area of Science:

• Nutritional Immunology
• Infectious Disease Epidemiology

Background:

• Iron deficiency and vitamin A deficiency are linked to increased infection morbidity and mortality.
• Existing research on these links is hampered by significant study design limitations.

Purpose of the Study:

• To review and critically assess the available evidence on the relationship between nutrient deficiencies (iron and vitamin A) and infection susceptibility.
• To clarify the role of iron status in infection, considering both deficiency and overload states.

Main Methods:

• Systematic review and critical analysis of published studies investigating iron deficiency, vitamin A deficiency, and infection outcomes.
• Evaluation of study methodologies to identify limitations and biases.

Main Results:

• Data are insufficient to establish a definitive causal link between iron deficiency or vitamin A deficiency and increased infection risk.
• Emerging evidence suggests iron deficiency states might be protective against certain infections like malaria and Yersinia.
• Iron overload, particularly from parenteral iron dextran in infants, may increase susceptibility to infections.

Conclusions:

• Current evidence is inconclusive regarding the role of iron and vitamin A deficiencies in predisposing to infection.
• Oral iron supplementation for iron deficiency anemia is not contraindicated based on available data.
• Further well-designed studies are needed to clarify the complex relationship between iron metabolism and infection immunity.